Programmable music synthesizer

ABSTRACT

A programmable music synthesizer which is completely electronic having no movable parts except for manually operated switches and controls wherein each note of a sequence of notes is digitally encoded in terms of a scaler value of the note, its time duration and relative octave range; the digitally encoded information being entered into an electronic memory via a keyboard comprising the manually operated switches and controls; the controls being further effective during the playback portion of the operation at which time the digitally encoded information is automatically withdrawn in accordance with the order in which the notes have been stored, a portion of the decoded information being used to selectively actuate a variable frequency generator the output of which appears as a predetermined sequence of musical notes each of which persists for a time duration in accordance with another portion of the prestored information.

1 1 Apr. 22, 1975 1 1 PROGRAMMABLE MUSIC SYNTHESIZER [76] Inventor:Charles A; Kapps, 27 University Mews, Philadelphia, Pa. 19104 22 Filed:Nov. 21, 1973 21] Appl. No.: 418,031

[52] U.S. Cl..' 84/l.0l; 84/103 [51] Int. Cl GlOh l/003G10h 5/00 [58]Field of Search 84/101. 1.03. 1.02. 1.28

[56] References Cited UNITED STATES PATENTS 3.515.792 6/1970 Dcutsch84/103 3.604.299 9/1971 Englund 84/103 3.610.799 10/1971 Watson 84/l.013.610.801 10/1971 Frcdkin ct a1. 84/103 3.639.913 2/1972 Watson 84/101 X3.683.096 8/1972 Peterson et a1. 84/].03 X 3.696.201 10/1972 Arsem cta1. 84/1.0l

3.697.661 10/1972 Dcutsch 84/101 3.743.755 7/1973 Watson 84/1013.755.608 8/1973 Dcutsch 1 84/l.01

3.763.364 10/1973 Deutsch ct a1 84/103 X 3.781.452 12/1973 Vauclain84/128 3.789.719 2/1974 Maillct 84/103 X 3.829.597 8/1974 Peterson cta1. 84/].03

TIME

D 36 I ECODER KEY BOARD BINARY ENCODER MEMORY OUTPUT REGISTER PrimaryExaminer-Richard B. Wilkinson Assistant E.raminerStanley J. WitkowskiAttorney. Agent. or Firm-Synnestvedt & Lechner [57] ABSTRACT Aprogrammable music synthesizer which is completely electronic having nomovable parts except for manually operated switches and controls whereineach note of a sequence of notes is digitally encoded in terms of asealer value of the note, its time duration and relative octave range;the digitally encoded information being entered into an electronicmemory via a keyboard comprising the manually operated switches andcontrols; the controls being further effective during the playbackportion of the operation at which time the digitally encoded informationis automatically withdrawn in accordance with the order in which thenotes have been stored, a portion of the decoded information being usedto selectively actuate a variable frequency generator the output ofwhich appears as a predetermined sequence of musical notes each of whichpersists for a time duration in accordance with another portion of theprestored information.

6 Claims, 3 Drawing Figures DECODER CLOC PATENTEUAPRZZlHYS 3.878.750

- sum 1 BF 3 ADVANCE KEY BOARD I? I6 [8 l9 BINARY ENCODER 22 LRIB5 B6 B7B8 5, B2 B3 B4 MEMORY OUTPUT REGISTER REST TIME DECODER TONE DECODERFIG. I

CLOCKI CLOC PIJENTED ZZ 3.878.750

SHEET 2 0F 3 3 D-TYPE FLIP FLOP D l C 0 CLOCK *1 INHIBIT \l \l/ \l!CLOCK ARII/ 5 7 PARALLEL H l OUTPUT w 7 I5 f COUNTER 4 BINARYMuLTIPLExER f DECODER 5 3 PARALLEL 2 2 flNPUT I I INPUT ENABLE 0 F|G.2TIME DECODER PROGRAMMABLE MUSIC SYNTHESIZER SUMMARY OF THE INVENTION Thepresent invention relates to a programmable music synthesizer and moreparticularly to a completely electronic implementation thereof having nomoving parts except for manually operated switches and controls. Anelectronic memory is provided for storing digital information defining asequence of notes including the value of each note relative to astandard musical scale, and also the octave and the time duration ofeach note. The digital information is entered into the electronic memoryduring the programming portion of an operative cycle. The storedinformation is recovered from memory during the playback portion of anoperative cycle. The scale and octave portions of the stored informationare used to generate an audio signal of desired frequency. The audiosignal persists for a predetermined time in accordance with the timeduration portion of the information stored with each note.

Prior art attempts to synthesize music are readily distinguishable fromthe present invention and as such may be generalized by classificationinto two categories: the first of which includes non-programmable musicsynthesizers an example of which is disclosed in the patent to Fredkinet al, U.S. Pat. No. 3,610,801; and secondly. devices comprising crudeanalogs of mechanical player pianos. which upon inspection will be foundto be lacking, among other things, any ability to control the relativetime relationship of the notes generated. Examples of the latter devicesinclude the subject of the patent to DAgata. U.S. Pat. No. 3,520,983 anda device called a Psych-Tone described in the Popular ElectronicsElectronic Experimcnter Handbook. 1973 Edition.

A programmable music synthesizer constructed in accordance with theprinciples of the present invention is readily adaptable for a widevariety of uses. Since a principal feature of the device is itsreprogrammable naturethis. coupled with the fact that the unit istotally self-contained. makes it particularly valuable as an aid incomposing music. The compact nature of the preferred embodiment of thepresent invention facilitates its use in this latter capacity.

Other uses of the subject invention include: the teaching of music. asan electronic music box. and as a musical door bell.

According to the present invention, the device for composing, recordingand playing back a sequence of musical notes comprises a keyboard therespective keys of which represent the notes capable of being generatedincluding the octave, the time duration of each note and the controlsignals for stepping the apparatus through its various modes ofoperation. The keyboard is operatively connected to a memory portionhaving a plurality of storage locations each of which is adapted tostore digital information defining a note in terms of its value on ascale of notes as well as the time duration and octave range of thenote. An address register is connected to the memory portion to permitthe storage locations of the memory to be sequentially scanned thusinitially facilitating the storage of digital information pertaining toa new sequence of notes; and subsequently thereto, during the playbackportion of an operative cycle, enabling the automatic and sequentialscanning of the plural memory locations at a rate determined by the timedurational information stored therein. For purposes of determining thetime duration of each note. a time decoder is connected to the output ofthe memory, an output signal being generated therefrom in accordancewith the time duration portion of the information stored at thatparticular memory location. The output of the time decoder is in turnused to step the address register such that upon the occurrence of eachoutput signal the address register is stepped; this in turn initiatesthe referencing of the next storage location in memory. Also connectedto the output of the memory is a tone decoder which is operative fromthe time a particular memory location is first referenced until suchtime as the time decoder generates an output signal to initiatereferencing of the next successive memory location. The tone decodergenerates an audio-signal having a frequency determined by the balanceof information contained at the memory storage location being referencedincluding the information defining the relative value of the note on themusical scale and its octave.

Although the preferred embodiment of the present invention has a limitedmemory capacity of some sixteen 8-bit words, with each word generating acorresponding note, it is possible to increase the memory capacitywithout altering the operating principles of the present inventionthereby enabling an entire musical score or a plurality thereof to beselectively playedback after having been programmed therein. Similarly,the preferred embodiment of the present invention is disclosed asembodying a single tone decoder. lt should be immediately apparent tothose having ordinary skill in the art that additional tone decoders maybe conveniently added so as to program the device to simultaneouslyreproduce a plurality of notes. By extending the design principles toinclude a plurality of time decoders the notes will be available forplayback in a time overlap manner. These and other features shouldbecome more readily apparent from the following specific description.

BRIEF DESCRlPTlON OF THE DRAWINGS FIG. 1 is a block diagrammaticrepresentation showing the principal operating portions of aprogrammable music synthesizer constructed in accordance with theprinciples of the present invention.

FIG. 2 is a detailed representation of the time decoder of FIG. 1.

FIG. 3 is a detailed representation of the tone decoder of FIG. 1.

DETAILED DESCRlPTlON OF THE INVENTION Turning now to FIG. 1, therein isillustrated a diagrammatic representation of the preferred embodiment ofthe subject programmable music synthesizer, the heart of which comprisesa memory 10. In the prefered embodiment, memory 10 comprises sixteen8-bit words selectively addressable on a half word basis. The firstthree bits of each word, corresponding to bits 8., B and B define thetime duration of a note i.e. how long the note or rest is to persist.These 3 bits facilitate eight possible time lengths; from a l6th note toa whole note. The means for selecting and determining the time length ofa note are discussed'in further detail below in connection withtheexplanation of FIG. 2.

The balance of the bits comprising'the 8 bit word are used to define theoctave; the relative value of a note within an octave; and, a possiblerest or stop condition. In the preferred embodiment bit B defines one oftwo octave ranges available; while bits B B B and B, are used to definethe relative value of a note within an octave as well as the stopand'rest conditions.

Memory 10 is perhaps most conveniently implemented using semiconductormemory chips which may be mounted on a mother-board thus facilitatingthe ready substitution of the memory portion of the apparatus. Suchsemiconductor memory chips are commercially available, an example ofwhich is presently being marketed by Fairchild SemiconductorManufacturing Co. under part number 93403. Each chip contains 16 fourbit words, thus two such chips are necessary to implement the memory inthe preferred embodiment.

The design of the subject music synthesizer is such that the memory 10may be readily enlarged. Thus, increasing the number of words in thememory 10 results directly in the increase of the number of notes whichmay be played back provided addressing means are available to addressall word locations in memory. Likewise, increasing the number of bits ineach word results in a corresponding increase in the amount and type ofinformation available to define each note.

Alternative modes of implementation of the memory 10 include the use ofstatic and dynamic shift registers. Another alternative concerns the useof read only memory techniques, these being particularly useful as ameans for cutting the unit price of a music synthesizer to be used as adoor bell or for some other application wherein there is no need tocontinuously update, or change, the sequence of notes. The use of a readonly memory nevertheless facilitates periodic reprogramming in the sensethat a different memory board may be readily substituted for the onecurrently in the unit. There is also the possibility of using areprogrammable" read only memory, such as that marketed by the IntelCorporation under number 1702A.

Addressing of the memory 10 is accomplished by means of an addressregister 12 which in the preferred embodiment of the present inventioncomprises a conventional four stage binary counter the output of'whichis capable of addressing anyof the sixteen storage locations of memory10. As will be noted from the explanation which follows, an output fromthe highest order stage of the address register 12 appears as a carry(C), the signal normally occurs after the highest order location inmemory 10 has been scanned. The carry signal serves to toggle a flipflop 14; this condition signals the completion of either the programmingor playback portion of an operative cycle of the music synthesizer.

The count stored in the address register 12 is advanced manually bymeans comprising an advance button 16, or alternatively is advancedautomatically by the output of a time decoder 13. The advance button 16is used to advance the address register 12 during the programmingportion of an operative cycle during which time information is beingstored in memory 10. Alternatively address register 12 is automaticallystepped by the output of the time decoder 13 during the playback portionof anoperation.

The sequencing of the address register 12 by means of the advance button16 enables the memory 10 to be selectively addressed for. arbitraryperiods of time during which digitally encoded information .may bestored in both half-words 'of 'the'memory address currently beingreferencedb'y the address'register. Storage on a half word basis iseffected, bythe selective actuation of I connected to the time decoder13. The clock functions to supply the time decoder with a continuousstream of periodic pulses which are employed in the time decoder togenerate synchronized output signals including the signal used to stepthe address register 12. The clock 15 utilized in the preferredembodiment of the present invention comprises a variable frequencyoscillator of conventional design having a controlled output which maybe varied over the range of 2 to 10 Hz. Although the clock 15 may beoperated at a variety of frequencies, the output thereof is generallyleft unchanged during the playback of any particular sequence of notes.The facility to vary the base frequency of the signal generated by clock1S affords an independent degree of control over the rate at which asequence of notes may be played back from the music synthesizer.

It should be noted that the signals generated by the advance button 16and the time decoder l3.are selectively gated into the address register12 by means of NAND gate 30 and AND gate 42 with the output of theadvance button being inhibited during the playback mode while outputsignals from the time decoder are inhibited during the reprogrammingmode.

Information is entered into the memory l0from a keyboard 21 via a binaryencoder 22. The keyboard 21 comprises 16 selectively actuatedmicroswitchesrepresenting the 16 notes capable of being played by thesubject device over a two octave range. The information comprising thenote selection is encoded in a conventional manner by means of thebinary encoder 22 into a four bit code which in turn is stored as a halfword in memory 10. Storage of a code representation of a selected notein memory 10 is accomplished by depressing a RIGHT WRITE key 19.Similarly a LEFT WRITE key 18 is provided to store an indication of theoctave range and the time duration of a note; onebit of the left halfword being used to determine the octave while the other three bits areused to determine how long a note, or rest, is to be. i 1

On the output side of the memory 10 is an output register 23 whichserves to buffer information from the memory to the time decoder 13 andtoa tone decoder 24. The tone decoder comprises a variable modulocounter which cycles at a varying rate depending upon the value of apreset count entered therein. The variablemodulo counter is driven by aconstant frequency clocking signal from a clock 26. As will be explainedbelow in. conjunction with the explanation of FIG. 3, the clock 26 iscapable of generating an output signal over a range of from 100 to 500kHz; however, during up or down. The stable output signal of the clock26 is divided into desired frequency components by the tone decoder 24which functions to generate a signal having a frequency corresponding tothe tone. or note, to be sults in the muting of the output of the tonedecoder 24 for a period of up to 1 full note. The occurrence of a stopcode indicates that there are no further notes in the particular tunebeing played.

The note being selected is entered into memory by simultaneouslydepressing the appropriate key on the keyboard 21 and the RIGHT WRITEkey 19. This automatically transfers a signal on the output linecorresponding to the selected key on the keyboard 21, which outputsignal is converted in the binary encoder 22 into a four bit binaryrepresentation which appears as bits B B B and B at memory 10 where itis stored as the right half of word 0.

The next step is to enter time" and "octave" information, correspondingto the note just selected, into the left half of memory word 0. This isdone by simultaneously depressing the LEFT WRITE control key and one ofthe 16 keys of the keyboard 21 representing the desired time and octaveselected in accordance with the provisions of Table l. A correspondingfour bit representation will be entered into bit locations B B B and Bof memory location 0.

It will be noted that in addition to the twelve notes entered into theright half of a memory word it is possi ble to enter a rest signal or astop code". As will become apparent from the explanation of thesynthesizer in its playback mode, the occurrence of a rest signal re-'reproduced. The manner of construction and mode of 5 After both theright and left half words have been enoperation of the tone decoder 24should become more tered into memory location 0 the Advance button 16readily apparent from the detailed discussion thereof is depressed thuspermitting a pulse to appear at the given below in conjunction with theexplanation of output of AND gate 30 which in turn steps the addressP16. 3. For now it should suffice to say that the output register 12 byone count thus referencing memory locaof the tone decoder 24 correspondsin frequency to a 10 tion 1.1nformation defining the second note in thetune particular musical note; the output signal being fed to is nowready to be entered into the right half word of a power amplifier 25 andfrom thence to a speaker 27. memory location 1 by means of theappropriate key on Consideration is now given to the execution of anopthe keyboard 21. This-operation is effected in the manerative cycle ofthe programmable music synthesizer of ner outlined above with respect tothe entry of similar FIG. 1 commencing with the programming portion 15information into the right half word of memory locathereof. For thispurpose a switch when set to PRO- tion 0. In similar manner the lefthalf word of memory GRAMMING MODE removes the ground or zerovoltlocation 1 receives information defining the time and age which inturn results in the partial conditioning of octave range of thecorresponding note. Thereafter the NAND gates 30. 32, and 34. Theselatter gates afford Advance button 16 is again depressed causing theadprotection against the accidental dumping" of mem- 20 dress register12 to reference memory location 2. This ory during the playback mode ofoperation. process is repeated until information has been stored in Alsoat this time a start button 17 is depressed which all sixteen locationsof memory 10. Alternatively. a

sets" flip-flop 14 thus activating the synthesizer. Just stop code maybe entered as desired.

prior to the setting of flip-flop l4, i.e. when the flip-flop Thiscompletes the explanation of the programming 14 is reset. the audiooutput of the tone decoder 24 is portion of the operation; however. itshould be noted muted, the address register 12 is reset, the memory 10that after the sixteenth note has been stored, in memis disenabled, andthe output of the time decoder 13 is ory location 15, and the advancekey is thereafter deinhibited. Thus. at such time as flip-flop 14becomes set pressed the resultant input to the address register 12 theaddress register 12 will register a count of 0. The causes the addressregister to recycle generating a carry Start signal conditions thecorresponding memory locasignal which is returned to the flip-flop 14causing it to tion to accept information from the keyboard 21 via bereset. When the control flip-flop 14 is reset it mutes the binaryencoder 22. The first information to be en the audio output. it resetsthe memory address counter tered into the keyboard 21 comprises therelative value to 0, it disenables the memory, and inhibits the timedeof a note which, in accordance with the representation coder. Nothingelse happens.

of Table l, is associated with a particular one of the 16 At i i now did to h operation f h keys comprising the keyboard 21. grammable musicsynthesizer in its playback mode.

TABLE 1 CON- KEY l 2 3 4 5 6 7 8 9 10 ll l2 l3 l4 l5 l6 PITCH C C SharpD D Sharp E F F Sharp G G Sharp A A Sharp B Rest Stcp LWEE-EIT/E TIME/1/16 A: 3/16 is k 5 l l/l6 A; 3/16 /4 it; i 1 WRITE OCTAVE LOWER OCTAVEUPPER OCTAVE This mode of operation is initiated by positioning switch20 to PLAY MODE. Subsequently, depressing the Start key 17 sets theflip-flop l4 and partially conditions NAND gate 40 and AND gate 42. Thetone decoder 24 will generate an output signal to the speaker 27corresponding in frequency to the note registered in the 0 word locationof memory 10, this latter information being buffered through the outputregister 23 of memory 10 and into the tone decoder 24 as informationbits 8,, B B B and B The corresponding time duration information isbuffered into the time decoder 13 as bits B B and B These latter bitsare decoded in the time decoder which generates a timed output signal inconsequence thereof which output signal completes the conditioning ofAND gate 42 thus stepping the address register 12 to memory location 1.In addition to stepping the address register the output of the timedecoder temporarily mutes the output of the tone decoder 24 so thatthere is a slight pause between notes. This latter feature permits thesame note to be played successively such that they appear as distinctnotes rather than as one long note. Succeeding notes are played in thesame manner with play continuing As indicated above. the time decoderserves to step the address register 12 during the playback mode ofoperation. The separation between successive stepping signals to theaddress register 12 determines the time duration of a note generated intone decoder 24. The information determining the separation betweensuccessive stepping pulses is derived from the time duration portion ofthe digital information stored in memory 10. i.e. the informationalcontents of bit locations 8,. B and B;,. This latter information is usedto selectively gate a particular one of a stream of pulses beinggenerated by the clock I onto the output line ofthe time decoder 13. Inthis respect clocking signals from clock 15 are used to toggle afour-stage counter 28 capable of generating. in timed sequence. a binarycoded representation of from 0 through 15; these latter signals arepartially decoded in logic 29 forming a corresponding number ofindependent signals. each of which occurs during respective successivestates of counter 28. In the preferred embodiment, only 8 of the 16signals generated by the decoding logic 29 are required since notes ofonly eight different time durations are provided for. The outputs of thedecoder 29 condition a conventional selection gating circuit 31 suchthat an output signal i's'generated therefrom upon coincidence with thedigitally encoded information stored in memory as bits B B and B Ineffect. the time decoder of FIG. 2 counts the signals generated by theclock and when a count corresponding to the count stored in memory 10 isreached, the time decoder generates an output signal to the addresscounter 12 resulting in the stepping of the latter to the nextsuccessive memory location.

To this end the time decoder of FIG. 2 is further provided with gatingcircuitry including NAND gates 35 and 37 and AND gate 39. The NAND gate35 permits the stepping of the counter 28 by clocking signals from clock15 only when flip flop 14 is set to the start state. NAND gate 37 andAND gate 39 function collectively to transfer an output signal from thetime decoder 13 to the address counter 12 and AND gate 38 of FIG. 1,only during the last half of a clock cycle during which coincidence isdetected in themultiplexer 31 between the input bits B B and B and thecount represented in counter 28. It is on the trailing edge of theoutput signal from AND gate 39 that the address register 12 isincremented. The trailing edge of the output signal from AND gate 39 ismade to persist for a sufficient length of time to ensure stability inAND gate 38 thus avoiding premature or accidental conditioning of thelatter. This may conventionally be effected by inserting a suitable timedelay at the input to AND gate 38. The counter I 28 is reset by thefirst clock pulse following the appearance of an enable signal from theoutput lead of the multiplexer 31. A flip fiop 33 is set by the firstclock pulse after the inhibit signal, generated at the output of ANDgate 36 of FIG. I, is removed. This prevents the starting of a playbackoperation until the beginning of a clock pulse, and insures that thefirst note will not have a variable length. i 1

Turning now to FIG. 3, therein are disclosed the details of the tonegenerator 24 of FIG. 1. The tone generator functions as a frequencydivider which uses the high frequency output signal from clock 26 as aninput to a frequency dividing network which in turn selectivelygenerates the desired frequency components cor-- responding-to themusical notes to be generated. The heart of the tone generator 24 is thevariable modulo counter 44. Counter 44 functions as a preset counterwhich is loaded with a predetermined count chosen such that thecomplement thereof when divided into the high frequency output of clock26 results inthe cycling of counter 44 at a rate equal to four times thefrequency of a note to be generated. This signal is in turn stepped downto two times the desired note frequency. i.e. one octave above thedesired note. by permitting the signal to toggle a complementary typeflip-flop. A further reduction to the desired frequency is obtained byusing the output of the aforementioned flip-flop as an input to a secondcomplementary type flip-flop. the note of desired frequency appearing atthe output thereof.

The synchronous counters 28 and 44 of FIGS. 2 and 3 respectively. areconstructed from integrated circuit four bit synchronous countersmarketed by Fairchild Semiconductor under catalog number 9316. Counter28 requires one unit and counter 44 requires two.

In the preferred embodiment of the present invention counter 44comprises an eight stage counter capable of generating an output signalevery 256 input clocking pulses. Thus, if a count of seven is presetinto counter 44., the first clock pulse to be inputted from clock 26will step the counter to a count of 8 such that an output signal will begenerated after some 249 clocking pulses. By dividing 249 into the basefrequency of 260.6 kHz and thereafter dividing the result by 4. there isproduced at the output of the tone decoder 24 a signal having afrequency of approximately 26 I .6 Hz corresponding to a middle C. Othernotes are similarly derived by entering a predetermined count intocounter 44 in accordance with the following Table of Values.

TABLE OF VALUES VARIABLE OUTPUT PRESET MODULO FRE- STANDARD FREQ. (EQUALTEMPERA- COUNT COUNT QUENCY NOTE MENT SYSTEM 7 249 261.6 C 26I .6 2I 235277.2 C sharp 277.2 34 222 293.4 D 293.7 46 2l0 3l0.2 Dsharp 3Il.l 58198 329.0 E 329.6 69 I87 348.4 F 349.2. I76 370.2 F sharp 370.0 90 I66392.5 G 392.0 99 I57 4l5.0 G sharp 4l5.3 I08 I48 440.2 A 440.0 I I6 I40465.4 A sharp 466.2

I24 I32 493.6 B 493.9

lish any desired predetermined count in the corresponding flip-flops ofthe modulo counter 44. It should be noted that after the predeterminedcount has been entered into the flip-flops comprising modulo counter44., the clocking signals from clock 26 step the counter along until anoverflow or carry is generated in the highest order stage. An outputfrom the highest order stage of the variable modulo counter 44re-establishes the predetermined count in the flip-flops. The countercontinues to cycle in this manner with every second output from thehighest order stage being used to toggle a flip-flop 49 to its set stateand correspondingly every fourth output of the highest order flip-flopof variable modulo counter 44 is used to toggle the flipflop 50 to itsset state.

Logical gating means comprising: a pair of NAND gates 52 and '54,inverters 56 and 58, and NAND gate 60, are partially conditioned by theoctave information comprising the bit 13,. The manner in which theselogic components cooperatively function with the outputs of flip-flops49 and 50 to deliver an output signal of desired frequency to the audioamplifier 25 of FIG. 1 and in turn to speaker 27 is explained below.

It will be noted that variable modulo counter 44 cycles at a ratedetermined by the complement of the preset count divided into the baseclock frequency of 260.6 kHz. Also, an output signal from the flip-flop49 partially conditions NAND gate 52 every second output pulse from thevariable modulo counter 44 while an output signal from flip-flop 50partially conditions NAND gate 54 every fourth output signal of thevariable modulo counter 44. The output of the in-line, inverters 56 and58 completes the conditioning of NAND gate 52 or NAND gate 54. Which ofthe NAND gates 52 and 54 is conditioned depends upon the state of theinput signal corresponding to bit 8,. Thus, if B, is low the signal onthe output side of inverter 58 will be high" thus conditioning NAND gate52. Under these same conditions the signal on the output side ofinverter 56 will be low" and as a consequence NAND gate 54 will not beconditioned. Conversely, if B is high" the output side of inverter 58will be low" while the output of inverter 56 will be high. Thus NANDgate 54 will be conditioned by NAND gate 52 will not. A low signal fromAND gate 36 de-conditions NAND gate 60, and prevents sound from beinggenerated during a REST. between notes, or when flip-flop 14 is reset.Alternatively, a high signal on the lnhibit lead to NAND gate 60,permits the audio signal being generated by NAND gates 52 and 54 toappear as an input to the audio amplifier 25 of FIG. 1.

While a preferred embodiment of the present invention has been disclosedand the operation has been described in terms thereof, it should bereadily apparent that various substitutions may be readily made withoutdeparting from the spirit of the invention. As an example. the tonegenerator 24 may conveniently be implemented by means other than avariable modulo counter. In similar fashion the keyboard may be alteredto vary the sequence of steps involved in the operation of the subjectsynthesizer in its PLAYBACK and PRO- GRAMMING modes. Accordingly, whilethe particular form of the device has been shown and described, it isnot intended that the scope of the invention be limited to theparticular form disclosed in that alternative forms of the device willimmediately be evident to those skilled in the art.

What is claimed is:

l. A music synthesizer comprising means to generate a digitalrepresentation corresponding to each one of a sequence of musical notes,said last named means further comprising first means to define thefrequency of each note and second means to define the time durationthereof, electronic means for separately storing each of said digitalrepresentations comprising said sequence of musical notes. and means forsequentially recovering each of said digital representations comprisingsaid sequence of musical notes from said electronic storage means. andmeans for generating from said digital representations audio signalscorresponding to said sequence of musical notes.

2. A music synthesizer operative to generate audio signals in the formof a sequence of musical notes from prestored digital representationsthereof, each of said prestored digital representations comprising afirst plurality of bit positions defining the frequency of a note and asecond plurality of bit positions defining the time duration thereof,electronic storage means, said prestored digital representations beingstored in said electronic storage means, and means operatively connectedto said electronic storage means for sequentially recovering saidprestored digital representations from said electronic storage means andfor generating from said digital representations audio signals in theform of said sequence of musical notes.

3. A programmable music synthesizer operable in a first mode to store aselected sequence of signals comprising preselected notes of a musicalscore and in a second mode to playback said stored signals comprisingsaid selected sequence of signals to thereby recreate said musical scoretherefrom, comprising means for generating a coded representation foreach of said preselected notes, said coded representation comprising aplurality of digitally encoded bits a first plurality of which definethe frequency of a note and a second plurality of which define the timerelationship of said note with respect to other of said preselectednotes, means operatively connected to said first named means for storingsaid coded representations of said preselected notes, and meansconnected to the output of said means for storing said codedrepresentations for recovering said coded representations of saidpreselected notes and for generating audio signals therefrom in saidselected sequence and bearing said predetermined time relationship withrespect to said other of said preselected notes.

4. A programmable music synthesizer operative to store a digitalrepresentation comprising a sequence of musical notes and wherein saiddigital representation comprises a plurality of digitally encoded bits21 first plurality of which defines the frequency of a note and a secondplurality of which defines the time duration thereof, said synthesizercomprising a keyboard adapted to enable an operator to sequentiallyselect a series of notes, digital encoding means operatively connectedto said keyboard for generating a digital representation of each of saidnotes as said notes are selected, electronic storage means operativelyconnected to said digital encoding means for sequentially storing thedigital representation corresponding to each of said series of notes inthe order in which said notes are selected by an operator of saidprogrammable music synthesizer, said last named means including means toautomatically scan the successive memory locations of said electronicstorage means at a rate determined by said second plurality of digitallyencoded bits comprising said digital representation of each note, andmeans operatively connected to said last named means for generatingaudio signals from said first plurality of digitally encoded bitscomprising said digital representation of each note.

5. A programmable music synthesizer comprising a keyboard comprising aplurality of selectively actuatable keys, each of said keys selectivelyrepresenting the pitch and time duration of a particular musical note. amulti-location electronic storage means. means for sequentially scanningsaid multi-location electronic storage means. means operativelyconnecting said keyboard and said multi-location electronic storagemeans. control means operatively connected to said scanning means and tosaid multi-location electronic storage means for sequentially storingdigital information defining the pitch and time duration of musicalnotes selected from said keyboard, said control means further operativeto initiate the scanning of the digital information stored in saidplural storage locations of said multilocation electronic storage means,said control means further comprising means for directing a firstplurality of bits of said digital information comprising a first portionof the informational contents of a particular one of said multi-storagelocations of said electronic storage means to a time decoder todetermine the time duration of a particular note and for directing asecond plurality of bits of said digital information comprising a secondportion of the information stored at said particular one of said pluralstorage locations of said electronic storage means to a tone decoder fordetermining the frequency of said note.

6. An apparatus particularly operative for composing musical scorescomprising a keyboard each key of said keyboard operative to generate asignal representing a particular note on a musical scale. said keysbeing further used to define the time duration of a particular noterelative to other notes and the octave in which the selected note is tobe played. storage means operatively connected to said keyboard andoperative to store a coded representation of each note selected via saidkeyboard including information defining the value of.

said note on said musical scale together with the octave and the timeduration of said note. addressing means operatively connected to saidstorage means and operative to sequentially scan the plural storagelocations of said storage means, and means for stepping said addressingmeans, said last named means further comprising manually actuated meansfor stepping said addressing means thereby sequencing said storage meansthrough said plural storage locations at a rate which facilitates entryof the coded representation of a note selected via said keyboard and asecond means for automatically stepping said addressing means at a ratedetermined by that portion of a signal entered via said keyboarddefining the time duration of a note relative to said other notes.

1. A music synthesizer comprising means to generate a digitalrepresentation corresponding to each one of a sequence of musical notes,said last named means further comprising first means to define thefrequency of each note and second means to define the time durationthereof, electronic means for separately storing each of said digitalrepresentations comprising said sequence of musical notes, and means forsequentially recovering each of said digital representations comprisingsaid sequence of musical notes from said electronic storage means, andmeans for generating from said digital representations audio signalscorresponding to said sequence of musical notes.
 1. A music synthesizercomprising means to generate a digital representation corresponding toeach one of a sequence of musical notes, said last named means furthercomprising first means to define the frequency of each note and secondmeans to define the time duration thereof, electronic means forseparately storing each of said digital representations comprising saidsequence of musical notes, and means for sequentially recovering each ofsaid digital representations comprising said sequence of musical notesfrom said electronic storage means, and means for generating from saiddigital representations audio signals corresponding to said sequence ofmusical notes.
 2. A music synthesizer operative to generate audiosignals in the form of a sequence of musical notes from prestoreddigital representations thereof, each of said prestored digitalrepresentations comprising a first plurality of bit positions definingthe frequency of a note and a second plurality of bit positions definingthe time duration thereof, electronic storage means, said prestoreddigital representations being stored in said electronic storage means,and means operatively connected to said electronic storage means forsequentially recovering said prestored digital representations from saidelectronic storage means and for generating from said digitalrepresentations audio signals in the form of said sequence of musicalnotes.
 3. A programmable music synthesizer operable in a first mode tostore a selected sequence of signals comprising preselected notes of amusical score and in a second mode to playback said stored signalscomprising said selected sequence of signals to thereby recreate saidmusical score therefrom, comprising means for generating a codedrepresentation for each of said preselected notes, said codedrepresentation comprising a plurality of digitally encoded bits a firstplurality of which define the frequency of a note and a second pluralityof which define the time relationship of said note with respect to otherof said preselected notes, means operatively connected to said firstnamed means for storing said coded representations of said preselectednotes, and means connected to the output of said means for storing saidcoded representations for recovering said coded representations of saidpreselected notes and for generating audio signals therefrom in saidselected sequence and bearing said predetermined time relationship withrespect to said other of said preselected notes.
 4. A programmable musicsynthEsizer operative to store a digital representation comprising asequence of musical notes and wherein said digital representationcomprises a plurality of digitally encoded bits a first plurality ofwhich defines the frequency of a note and a second plurality of whichdefines the time duration thereof, said synthesizer comprising akeyboard adapted to enable an operator to sequentially select a seriesof notes, digital encoding means operatively connected to said keyboardfor generating a digital representation of each of said notes as saidnotes are selected, electronic storage means operatively connected tosaid digital encoding means for sequentially storing the digitalrepresentation corresponding to each of said series of notes in theorder in which said notes are selected by an operator of saidprogrammable music synthesizer, said last named means including means toautomatically scan the successive memory locations of said electronicstorage means at a rate determined by said second plurality of digitallyencoded bits comprising said digital representation of each note, andmeans operatively connected to said last named means for generatingaudio signals from said first plurality of digitally encoded bitscomprising said digital representation of each note.
 5. A programmablemusic synthesizer comprising a keyboard comprising a plurality ofselectively actuatable keys, each of said keys selectively representingthe pitch and time duration of a particular musical note, amulti-location electronic storage means, means for sequentially scanningsaid multi-location electronic storage means, means operativelyconnecting said keyboard and said multi-location electronic storagemeans, control means operatively connected to said scanning means and tosaid multi-location electronic storage means for sequentially storingdigital information defining the pitch and time duration of musicalnotes selected from said keyboard, said control means further operativeto initiate the scanning of the digital information stored in saidplural storage locations of said multi-location electronic storagemeans, said control means further comprising means for directing a firstplurality of bits of said digital information comprising a first portionof the informational contents of a particular one of said multi-storagelocations of said electronic storage means to a time decoder todetermine the time duration of a particular note and for directing asecond plurality of bits of said digital information comprising a secondportion of the information stored at said particular one of said pluralstorage locations of said electronic storage means to a tone decoder fordetermining the frequency of said note.